Method of securing electrical component leads to a support



Aug. 10, 1965 .J. o. RENSKERS 3, 7

METHOD OF SECURING ELECTRICAL COMPONENT LEADS TO A SUPPORT Original Filed Aug. 17, 1959 INVENTOR. Joqid o. @awsmaas BY rrow z United States Patent 3,l *,178 METHUD 9F SECURHNG ELEQTREQAL CGMPG- NENT lJEAlJS Tit} A. SUE ESRT John (3-. llenskers, Crystal Latte, ilk, assignor to Coilcrat't, Inc, Cary, lit, a corporation oi iliinois Grigiual application Aug. 17, H59, Ser. No. 834,397. Divided and this application Apr. 22, 1953, Ser. No. 274,675

9 Claims. (Cl. 29-15556) My invention relates to a method for making coils and transformers and more specifically to a method for assembling coil and transformer windings to a coil form. This application is a division of my copending application Serial No. 834,307, filed August 17, 1959, entitled A Coil Form, a Method for Making Coils and Transformers, and the Coils and Transformers So Made.

in printed circuitry employed by the radio and television industry, certain coil and transformer windings are mounted to a coil form having a flange at one end with the leads of the windings extending through the flange. My invention is directed to the assembly of such windings to a form of this character.

A major object of my invention may therefore be considered to be a method of assembling windings to a flanged coil form to make coils and transformers which is quicker, less expensive and more accurate than methods hitherto employed.

My invention is characterized by the absence of any adhesives separate from the coil form itself.

My method or process is notable for the accomplishment of the dual functions of securing the windings to the coil form simultaneously with tinning the ends of the leads thereof to save a multiplication of processing steps and a double handling of the coils or transformers.

A consequence of the practice of my invention is a novel and unique provision for spacing the coil or transformer so made above the printed circuit board or chassis to which it is to be attached, for ventilation, the avoidance of condensation, and additional cooling.

Other objects and advantages of my invention will be apparent from the following description and drawings of which:

FIG. 1 is a side elevation of a transformer made in accordance with the method of my invention;

PEG. 2 is a side elevation of the secondary coil of FIG. 1;

FIG. 3 is a side elevation of the inner, primary coil of FIG. 1 rotated from the showing of FIG. 1 to illustrate the offset of the leads thereof;

FIG. 4 is a bottom plan view of the coil form of FIG. 1 shown with the coil leads projecting therefrom;

FIG. 5 is a fragmentary vertical section through the coil form taken substantially along the line 55 of 1 1G. 4;

FIG. 6 is a view similar to the right hand portion of FIG. 5, showing, however, a coil lead anchored in the coil form;

FIG. 7 is a fragmentary vertical section through the transformer of FIG. 1 showing the leads thereof immersed in a tinning bath in accordance with the method of my invention; and

FIG. 8 is a view similar to FIG. 1 of a coil embodying my invention.

In FIG. 1 is shown a transformer consisting generally of a coil form 12, a primary coil 14 and a secondary coil 16 surrounding and overlying the primary coil 14-. The coil form 12 is made of a thermoplastic insulating material such as nylon, polyethylene and the like, and includes a tubular post 13 which extends through the coils and an annular skirt or flange 2% extending about the ilhddld Fatented ll), 1965 lower end thereof. The post 18 may have internal provision for adjustably mounting a core, but as such provisions are Well known in the art and play no part in my invention it has not been illustrated.

The top surface 22 of the skirt 2i is peripherally dimpled to provide a plurality of conical depressions 24 in the upper surface, there being six such depressions in the illustrated embodiment, and corresponding conical projections as on the under side 28 of the skirt. Holes 30 are formed through the skirt in the bottoms of the conical depressions. The holes are proportioned to be somewhat larger than the coil leads which they are to con tain. Slots 32 may be formed in the edge 34 of the skirt to extend to each of the holes 36. The slots are desirably formed to extend at a substantial angle away from the radial with respect to the skirt to meet the holes so at points spaced inwardly from the outermost edges thereof. It will be appreciated, however, that the slots are not essential to the practice of my invention and may be omitted.

The coils of the described transformer are illustrated in FIGS. 2 and 3. FIG. 2 shows the secondary coil which is the outer coil of PEG. 1. This consists of a helical Winding 3 of insulated wire with the bottom lead 3% thereof bent through a right angle to extend downward from the coil and the upper lead as bent likewise through a right angle to extend down outside the coil 36 and project therebelow parallel to the axis of the coil. The leads may be olfset outwardly as needed to enter the ap propriate holes 39' in the skirt Zil.

The primary coil 14- of PEG. 3 includes a helical Winding 42 of smaller radius than the radius of the secondary coil 16 so that it may be inserted within the secondary coil, and of sufiicient inside diameter to fit over post 18 of the coil form. The lowermost lead 4-4 of the primary coil extends outwardly as at as from the coil and then downward as at 43. The upper lead 5t of the coil projects outwardly from the coil as at 52 and extends downwardly as at 5'4- to extend below the helix 42. The outward extensions 46 and 52 of the two leads is for the purpose of spacing the leads properly for reception in the holes so and the outward extension 52 is for the additional purpose of permitting the reception of the secondary coil 16 between the helix 4?. of the primary coil 1 and the upper lead thereof 5d.

The assembly of these components is believed evident from their description. The primary coil 14 is inserted in the secondary coil 16 and the two assembled coils dropped over post 13 of the coil form 12. The downwardly projecting leads 38, 4d, 4d and 5% may be guided into certain prearranged holes 30 in skirt 20 so that a particular orientation of leads, either absolute or relative, pertains according to the coil users specifications. Should it be the case that the leads are not axial or properly spaced from the axis of the coil or oriented inaccurately for the direct insertion into holes Sil as will most likely be the situation, the leads may be inserted into the holes 3% subsequent to the deposit of the coils on the post 18 and the seating thereof against skirt 2% by snapping the leads through slots 32 into the appropriate holes 3t Following the assembly of the windings to the coil form, the leads are tinned and the windings secured to the coil form in a single operation. This, is achieved by dipping the leads in a tinning bath as illustrated in FIG 7. The tinning bath is simply a receptacle 56 having a molten tinning composition 58 therein. The insulation of the wire used in coil manufacture is generally thermoplastic and the tinning dip strips back the insulation with immersion of the leads in the bath. My invention resides in dipping the leads of the assembled but not yet completed transformer as described above into the tinning bath s0 that the surface of the tinning bath touches or nearly touches the conical downward projections 26 encircling the leads in holes 30. The thermoplastic material of which the coil form flange is made melts and closes about the leads as illustrated in Fig 6.

The exact depth of the immersion is generally not critical. If the transformer is dipped so as to immerse slightly the projections 26, the lower ends thereof will melt and float to the surface of the bath and fill in around the leads. If the clipping is such that the projections are spaced slightly above the surface of the bath, there will still be an effective heat transfer to the projections by radiation from the surface of the bath and by conduction up the leads to cause a similar softening and fiow of the plastic sufficient, upon cooling, to bond the leads within the skirt for purposes of lead anchorage as illustrated in FIG. 6.

Removal of the leads and subsequent cooling of the transformer skirt material then anchors the coils to the coil form by their leads and insures a precise angular relation of the leads and a relatively exact cylindrical extension thereof from the baseof the coil form well suited for inesrtion in a printed circuit board. The plastic of the projections bonds successfully to bare Wire, but particularly Well to the insulation on the wire.

Since the leads are anchored in thescoil form skirt 29 close to their ends, the leads have substantial stiifness and are well able to withstand bending forces which may arise in subsequent handling. Should the leads be bent'in 5 handling they may easily be straightened again without destroying the seal between the leads and the coil form skirt.

In the tinning process I find that the slots, particularly the non-radial slots shown, usually heal themselves and flow closed.

It will be noted in FIG. 6 that the conical downward extensions 26 are not completely leveled in the tinning dip but rather, as may be seen in FIG. 1, the leads extend from what may be considered small bosses 60, the residues of the projections 26. This is a characteristic'deliberately sought and controlled by the depth of the immersion of the transformer leads into the tinning bath. In printed circuits it is desirable for ventilation and the avoidance of condensation between the mounting board and attached components or circuit elements, that such elements be spaced slightly above the surface of the mounting boards, and the radial bosses 60 meet excellently this spacing function. I

It is believed that the structure of the coil illustrated in FIG. 8 will be readily understood from the foregoing description of the transformer. The coil 61 is illustrated as being constructed on the same coil form 62 described in conjunction with the transformer. In this case, a single helical winding 64 is placed on the tubular post 66 ofthe coil form to abut at its lower end against skirt 68 of the form. The free ends 70 and 72 of the winding are passed through the desired holes in the coil form skirt either directly or by forcing them through slots identical with slots 32 of FIG. 4. Free end or lead 72 constitutes the upper free end of the winding 64 and is carried down the outside of the winding to extend below the coil form skirt as illustrated. The leads of the assembled winding and form are then tinned as described before to seal the conical projections identical with projections 26 of the transformer structure about the leads 70 and 72 and so create the bosses 74.

scribed the sealing of the leads in the holes 30'as a part of a lead tinning dip, this sealing may be effected independently by dipping the ends of the projections in a bath of any appropriate fluid capable of being heated enough to cause the requisite softening or melting. Thus where tinning of the leads may not be required, a dip may be employed for this purpose alone. I therefore desire that my invention be regarded as being limited only as set 5 forth in the following claims.

I claim:

1. A method of assembling an electric winding to a coil form, said winding having ends formed to extend beyond one end of said winding and parallel to the axis of said winding, said coil form including a thermoplastic, insulating skirt adapted to have said winding mounted against one side thereof and having apertures therethrough to receive said ends of said winding, said apertures being closely surrounded on the other side of said skirt by annular projections; which comprises inserting said ends of said windingin said apertures to extend through and beyond said skirt and bring said winding into mounted relation with said one side of said skirt, dipping said ends in a molten tinning bath a sufficient distance to bring the surface of said bath in contact with said projections to melt said projections and float the material thereof into said apertures and into intimate contact with the end portions contained in said apertures ,1 and withdrawing said ends from said bath to permit said material to solidify and seal said end portions in said apertures.

2. The method as set forth in claim 1 wherein each of said ends are dipped in said tinning bath a less distance than full immersion of said projections to leave a part of each of said projections unmelted and still projecting.

3. A method of assembling an electric winding to a coil form, said winding having ends formed to extend beyond one end of said winding and parallel to the axis of said winding, said coil form including a thermoplastic, insulating skirt adapted to have said winding mounted against one side thereof and having apertures therethrough to receive said ends of said winding, said apertures being closely surrounded on the other side of said skirt by an: nula-r projections; which comprises inserting said ends of said winding in said apertures to extend through and beyond said skirt and bring said winding into mounted relation with said one side of said skirt, dipping said ends in a hot liquid bath a suflicient distance to bring the surface of said bath in contact with said projections to melt said projections and float the material thereof into said apertures and into intimate contact with the end portions contained in said apertures and withdrawing said ends from said bath to permit said material to solidify and seal said end portions in said apertures.

4.'A method of assembling electronic components having at least two downwardly extending leads there from to one side of a thermoplastic, insulating base, said base having at least as many apertures therethrough as said leads arranged in a relation dependent on the ultimate desired relation of said leads, said base having annular projections on that side thereof other than the side to which said component is assembled immediately surrounding said apertures, which comprises extending said leads into, through and substantially beyond those apertures conforming to said relation, immersing said extended ends of said leads in a molten tinning bath a distance sufficient to bring the ends of said projections into contact with the surface of said bath to melt the ends of said projections and float the melted, thermoplastic, projection material into said apertures and about the portion of said leadscontained within said apertures, and withdrawing said leads from said tinning bath to permit said melted projection material to solidify in said apertures to seal saidrlead portions in said base. i

5. In a circuit component including a molded synthetic thermoplastic support member having a central post portion and a radially extending flange portion at one end of the post portion, wherein the face of the flange portion opposite from the post portion has a plurality of circum- 5 ferentially spaced substantially conical projections exarssars tending axially therefrom and wherein said flange portion and said conical projections have holes extending theretbrough, and a helically Wound coil having terminal leads extending axially from one end thereof, the method of assembling said circuit component comprising, inserting said helically wound coil over said post portion with the axially extending terminal leads axially extending through the holes in said flange portion and said substantially conical projections and axially projecting beyond said substantially conical projections, and dipping the projecting ends or" said axially extending terminal leads in a molten tinning bath for heating and tinning the same and for heating the substantially conical projections to cause the same to seat flow and fill the holes therein about the axially extending terminal leads in said flange portion and substantially conical projections.

6. A method of assembling an electric winding to a coil form, said winding having ends formed to extend beyond one end of said winding and parallel to the axis or" said winding, said coil form including a post and a thermoplastic insulating skirt at one end of said post, said post being adapted to have said winding mounted thereon, said skirt having apertures therethrough to receive said ends of said winding, said apertures being closely surrounded on the other side of said skirt by integral annular projections tapering downwardly to an edge; which comprises mounting said winding on said post and inserting said ends of said winding in said apertures to extend through and beyond said skirt, dipping said ends in a hot liquid bath to cause said edges of said projections to melt and flow into intimate contact with the end portions contained in said apertures, and withdrawing said ends from said bath to permit the melted thermoplastic projection material to solidify and seal said end portions in said apertures.

7. The method as set forth in claim 6 wherein said hot liquid bath is a molten tinning bath.

3. A method of assembling an electric component having at least two leads to a thermoplastic flat mounting member having apertures therethrough to receive the leads of said component, said apertures being closely surrounded on one side of said member by integral annular projections tapering downwardly to an edge; which comprises inserting the leads of said component into said apertures with the free ends thereof extending outward from said projections, immersing said ends in a molten tinning bath to cause said edges only of said projections to melt and flow into intimate contact with the lead portions contained in said apertures, and withdrawing said ends from said bath to permit said melted thermoplastic projection material to solidify and seal said lead portions in said apertures.

9. A method of assembling an electric component having two leads to a thermoplastic fiat mounting memher having apertures therethrough to receive the leads of said component, said apertures being closely surrounded on one side of said member by annular projections; which comprises inserting the leads of said component into said apertures with the free ends thereof extending outward from said projections, immersing said ends in a molten tinning bath a suflicient distance to bring the tip of each of said projections into contact with the bath surface to cause the tips of said projections to melt and float into intimate contact with the lead portions contained in said apertures, and Withdrawing said ends from said bath to permit said melted tips to solidify and seal said lead portions in said apertures References flited by the Examiner UNITED STATES PATENTS 2,941,172 6/60 Sutton 336-192 FOREIGN PATENTS 753,875 8/56 Haftung.

JOHN F. CAMPBELL, Primary Examiner.

WHITMORE A. W'ILTZ, Examiner. 

5. IN A CIRCUIT COMPONENT INCLUDING A MOLDED SYNTHETIC THERMOPLASTIC SUPPORT MEMBER HAVING A CENTRAL POST PORTION AND A RADIALLY EXTENDING FLANGE PORTION AT ONE END OF THE POST PORTION, WHEREIN THE FACE OF THEW FLANGE PORTION OPPOSITE FROM THE POST PORTION HAS A PLURALITY OF CIRCUMFERENTIALLY SPACED SUBSTANTIALLY CONICAL PROJECTIONS EXTENDING AXIALLY THEREFROM AND WHEREIN SAID FLANGE PORTION AND SAID CONICAL PROJECTIONS HAVE HOLES EXTENDING THERETHROUGH, SAND A HELICALLY WOUND COIL HAVING TERMINAL LEADS EXTENDING AXIALLY FROM ONE END THEREOF, THE METHOD OF ASSEMBLING SAID CIRCUIT COMPONENT COMPRISING, INSERTING SAID HELICALLY WOUND COIL OVER SAID POST PORTION WITH THE AXIALLY EXTENDING TERMINAL LEADS AXIALLY EXTENDING THROUGH THE HOLES IN SAID FLANGE PORTION AND SAID SUBSTANTIALLY CONICAL PROJECTIONS AND AXIALLY PROJECTING BEYOND SAID SUBSTANTIALLY CONICAL PROJECTIONS, AND DIPPING THE PROJECTING ENDS OF SAID AXIALLY EXTENDING TERMINAL LEADS IN A MOLTEN TINNING BATH FOR HEATING AND TINNING THE SAME AND FOR HEATING THE SUBSTANTIALLY CONICAL PROJECTIONS TO CAUSE THE SAME TO HEAT FLOW AND FILL THE HOLES THEREIN ABOUT THE AXIALLY EXTENDING TERMINAL LEADS IN SAID FLANGE PORTION AND SUBSTANTIALLY CONICAL PROJECTIONS. 